Thin film forming apparatus and thin film forming method

ABSTRACT

Prior to the start of transfer of an insulation film to a substrate, the degree of opening of a butterfly valve is set small so that evaporation of a solvent component contained in the insulation film is suppressed and the fluidity of the insulation film is ensured at the start of the transfer. On the other hand, the butterfly valve is totally opened at the start of the transfer, so that the pressure inside a thin film forming chamber rapidly decreases and transfer of the insulation film to the substrate is performed always in a low-pressure state (high-degree of vacuum).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film forming apparatus and athin film forming method, which require to press a substrate and a sheetfilm against each other within a thin film forming chamber so that athin film, such as an insulation film, disposed on the sheet film inadvance is transferred onto the substrate and a thin film is accordinglydisposed on the substrate.

2. Description of the Related Art

Over the recent years, it has became necessary to use a thin filmforming method suitably applicable to a large area size as wafers forthe manufacture of LSIs have became larger in diameter, liquid crystalpanels have became larger in area size, etc. In addition, in the fieldof multilevel interconnections techniques for manufacturing LSIs, as thesurface of an insulation film needs be planarized accurately to realizemultilevel interconnections. It is not only necessary to handle anincrease in surface area but surface planarization techniques to formthin films as well are in an increasing demand. In an effort to satisfythese requirements, thin film forming techniques for forming a thin filmon a substrate by a pressure transfer method have been proposed.

This type of thin film forming apparatus may be an apparatus which isdescribed in Japanese Patent Application Laid-Open Gazette No.H10-189566 for instance. In this apparatus, a specimen holder comprisinga built-in heater is disposed within a thin film forming chamber whichis located inside a processing container. A semiconductor wafer, a glasssubstrate for liquid crystal panel or the like (hereinafter referred as“substrate”) on which a thin film is to be formed can be held on thespecimen holder. Further, a transfer plate is disposed below thespecimen holder so as to face the specimen holder within the thin filmforming chamber, and holds the sheet film with the thin film, which isdisposed on the sheet film so that the thin film faces to the substrate.Like the specimen holder, the transfer plate as well comprises a heater,so that it is possible to heat up the sheet film which is held on thetransfer plate.

A vacuum pump is linked to the thin film forming chamber. The substrateis held on the specimen holder and the sheet film is held on thetransfer plate, and after the thin film forming chamber is closedair-tight, the thin film forming chamber is evacuated by the vacuumpump. Following this, while evacuating and depressurizing the thin filmforming chamber by the vacuum pump, the specimen holder holding thesubstrate and the transfer plate holding the sheet film are moved closerto each other. Thus, the substrate and the sheet film are pressedagainst each other, and the thin film on the sheet film is transferredonto the substrate. As the thin film is disposed on the substrate inthis manner, after moving the substrate and the sheet film back to theiroriginal positions, the thin film forming chamber is returned back tothe atmospheric pressure. Finally, the substrate with the thin film andthe sheet film without the thin film are unloaded out from theprocessing container.

By the way, in a conventional thin film forming apparatus of thepressure transfer method, after setting the substrate and the sheet filmrespectively to the specimen holder and the transfer plate, the vacuumpump starts to evacuate and depressurize the thin film forming chamber.Simultaneously with evacuating and depressurizing, transfer of the thinfilm to the substrate is executed. However, in the conventionalapparatus, while the thin film forming chamber is simply evacuated anddepressurized by the vacuum pump, there is no special considerationgiven on the pressure inside the thin film forming chamber (degree ofvacuum) as it is before and during the transfer, thus leaving a room forimprovement for excellent creation of a thin film. For instance,although the thin film needs to have a certain level of fluidity so asto be transferred favorably to the substrate, as the pressure inside thethin film forming chamber is largely reduced prior to the start of thetransfer, a solvent component contained in the material of the thin filmevaporates in a great quantity owing to the lowered pressure inside thethin film forming chamber. The fluidity of the thin film therefore wouldhave deteriorated by the time the transfer starts, thereby making itimpossible to favorably transfer the thin film to the substrate in somecases. Conversely, but for sufficient depressurization of the thin filmforming chamber during transfer, the transfer of the thin film to thesubstrate could leave a void between a pattern formed in the substrate,such as a contact hole, and the thin film, in which case excellenttransfer becomes impossible. Thus, an optimal value of the pressureinside the thin film forming chamber is different between before andduring the transfer, and hence, in order to execute excellent transfer,it is important to flexibly and precisely control the pressure insidethe thin film forming chamber. Despite this, such pressure control isdifficult in the conventional apparatus.

SUMMARY OF THE INVENTION

A major object of the present invention is to provide a thin filmforming apparatus and a thin film forming method, with which it ispossible to favorably transfer a thin film to a substrate.

In fulfillment of the foregoing object, a thin film forming apparatusand a thin film forming method are provided and are particularly wellsuited to excellent transfer of a thin film, which is formed on a sheetfilm, to a substrate. A pressure value (degree of vacuum) desired forexecution of excellent transfer is different between before and duringtransfer of a thin film to a substrate. Hence, the pressure inside athin film forming chamber is controlled to proper values before andduring transfer according to the present invention.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the sameis read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for purpose ofillustration only and is not intended as a definition of the limits ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing of a first preferred embodiment of a thin filmforming apparatus according to the present invention;

FIG. 2 is a partially expanded cross sectional view of the thin filmforming apparatus shown in FIG. 1;

FIG. 3 is a drawing which shows operations of the thin film formingapparatus shown in FIG. 1;

FIG. 4 is a drawing of other preferred embodiment of the thin filmforming apparatus according to the present invention; and

FIG. 5 is a drawing which shows operations of the thin film formingapparatus shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a drawing of a first preferred embodiment of a thin filmforming apparatus according to the present invention. FIG. 2 is apartially expanded cross sectional view of the thin film formingapparatus shown in FIG. 1. This thin film forming apparatus comprises aprocessing container 1 whose inside is a thin film forming chamber 11 asdescribed later which is for performing transfer. Further, an exhaustvent 12 is formed in a side bottom surface of the processing container1, and a pressure control unit 2 which adjusts the pressure inside thethin film forming chamber 11 is connected to the exhaust vent 12.

In the pressure control unit 2, a vacuum pump 22 is linked to the thinfilm forming chamber 11 via a butterfly valve 21. When the butterflyvalve 21 is open and the vacuum pump 22 works in accordance with anoperation signal received from a control unit 3 which controls theentire apparatus, the thin film forming chamber 11 is evacuated anddepressurized. In addition, the pressure control unit 2 comprises avalve controller 23 which controls the degree of opening of thebutterfly valve 21. The valve controller 23 controls opening and closingof the butterfly valve 21 to adjust the amount of valve opening inaccordance with a valve opening signal received from the control unit 3.Thus, the volume of exhaust air from the thin film forming chamber 11per unit time is adjusted and the pressure inside the thin film formingchamber 11 (degree of vacuum) is controlled. As described above,according to this embodiment, the butterfly valve 21, the vacuum pump 22and the valve controller 23 respectively function as “exhaust adjustingunit,” “exhausting unit” and “pressure adjusting unit” and the pressureinside the thin film forming chamber 11 is therefore adjustable.According to this embodiment, for the purpose of accurately controllingthe pressure inside the thin film forming chamber 11, a pressure gauge31 is disposed to measure the pressure inside the thin film formingchamber 11. A result of the measurement obtained by the pressure gauge31 is outputted to the control unit 3, and feedback control based on themeasurement result is executed.

Further, an inlet 13 is formed in a top peripheral portion of theprocessing container 1, which allows to supply nitrogen gas flowing at aconstant rate into the thin film forming chamber 11 through the inlet13. In short, the inlet 13 is connected with a nitrogen gas supplyingsource (not shown) via a mass flow controller 14, and the mass flowcontroller 14 controls the inflow of nitrogen gas which is supplied tothe thin film forming chamber 11 through the inlet 13. Although thisembodiment requires to supply nitrogen gas for the purpose of realizingexcellent transfer as described later, the type of gas to be supplied tothe thin film forming chamber 11 is not limited to this but may be anygas which is appropriate for the process of transfer.

In the thin film forming chamber 11 whose pressure is adjusted, a firstand a second plates 4 and 5 are housed one above and the other below soas to face with each other. Of these plates, the first plate 4 iscapable of holding a substrate W, on which a thin film is to bedisposed, on a lower surface of the first plate 4 faced with the secondplate 5, and thus serves as “substrate holding means” of the presentinvention. The substrate W may comprise a semiconductor wafer formed inthe shape of a disk and aluminum interconnection which is patterned asan electrode interconnection on the semiconductor wafer, for instance.An example that an insulation film (thin film) described later istransferred onto the pattern-bearing surface of the substrate W will nowbe described.

A quartz plate 41 polished to achieve a planar surface is disposed tothe lower surface of the first plate 4, and the substrate W is disposedon the quartz plate 41. The reason of using quartz as the material ofthe plate 41 which directly contacts the substrate W is because quartzdoes not contain a substance which contaminates the substrate W andbecause quartz can be easily worked on and planarized easily to anecessary degree.

Further, a heater 6 is disposed as heating means inside the first plate4. The heater 6 is controlled to a temperature between 25° C. and 300°C. by a heater controller 61 based on a substrate temperature signalreceived from the control unit 3. The first plate 4 is hung inside theprocessing container 1 in such a manner that the first plate 4 can beraised and lowered by a load motor 71.

The other one of the plates, namely, the second plate 5, is disposedbelow the first plate 4 in such a manner that the axis of the secondplate 5 matches with that of the first plate 4. A sheet film 8 is heldon an upper surface of the second plate 5, and the second plate 5functions as “film holding means” of the present invention. Moreprecisely, the second plate 5 comprises a main plate 51, a quartz stage52 which is capable of holding the sheet film 8 on an upper surface ofthe main plate 51, and heating lamps 53 which heat the sheet film 8. Thesheet film 8 is formed in the shape of a circle which is larger than thesubstrate W, and an insulation film 81 which is a thin film is formed ona surface of the sheet film 8. As the sheet film 8, a thermoplasticresin film 82 is used in this embodiment. The insulation film 81 isobtained by applying on the sheet film 8 a coating fluid of an SOGmaterial for forming insulation film into the thickness of 1 μm or more.The insulation film 81 is used as the thin film.

On the upper surface side of the main plate 51, a concave 511 is formed.The plane size of the concave 511 is slightly larger than that of thesubstrate W and is directed toward the first plate 4 as shown in FIG. 2.The four heating lamps 53 are buried inside the concave 511, and thequartz stage 52 is located at the position of the opening of the concave511. The sheet film 8 can be placed on an upper surface of the quartzstage 52 in such a manner that the insulation film 81 disposed on thesheet film 8 is directed toward the substrate W which is held on thefirst plate 4.

A film holding/straining unit 9 is disposed at the periphery of the mainplate 51, so as to hold the sheet film 8 mounted on the quartz stage 52during transfer of the insulation film 81 and to strain the sheet film 8at the timing described later.

In addition, as shown in FIG. 1, the heating lamps 53 are electricallyconnected with a lamp controller 54, and the lamp controller 54 controlsturning on and turning off of the heating lamps 53 based on a lampcontrol signal which is received from the control unit 3. Hence, as thelamp control signal which demands to turn on the heating lamps 53 issupplied from the control unit 3 to the lamp controller 54, the heatinglamps 53 turn on and heat waves emitted from the heating lamps 53 passthrough the quartz stage 52 and irradiate the sheet film 8. This heatsup the sheet film 8 to a temperature between 25° C. and 300° C.

Meanwhile, the second plate 5 is elastically supported by a plurality ofcompression coil springs 73 on a support plate 72, so that the loadedpressure of pressing the substrate W and the sheet film 8 against eachother becomes uniform. Further, the support plate 72 is structured insuch a manner that support columns 74 hold the support plate 72 for freeupward and downward movements, and that the support plate is accordinglyraised and lowered by a load motor 75. According to this embodiment, athin film forming process (transfer processing) which will be describednext is performed while raising and lowering the two plates 4 and 5 inmutually opposite directions by means of the load motors 71 and 75, andthe load motors 71 and 75 serve as “loading means” of the presentinvention.

The thin film forming process using the thin film forming apparatusabove will now be described. According to this embodiment, the substrateW is mounted with its pattern-bearing surface (surface in which theelectrode interconnection is formed) directed to below to the lowersurface of the first plate 4. Meanwhile, the sheet film 8 denoted at thedashed line shown in FIG. 2 is supplied with the insulation film 81directed to above over the stage 52 of the second plate 5, and an outerperipheral portion of the sheet film 8 is held by the filmholding/straining unit 9. At this stage, the film holding/straining unit9 does not strain the sheet film 8 yet.

As the substrate W and the sheet film 8 are loaded in and mounted (timet1) in this manner, the control unit 3 controls the respective portionsof the apparatus in accordance with a transfer program which is storedin a memory (not shown) in advance, and the transfer processing is thenexecuted to thereby transfer the insulation film 81 to the substrate W.The transfer processing will now be described in detail with referenceto FIG. 3. The graph in FIG. 3 shows the pressure inside the thin filmforming chamber 11, wherein the thick solid line denotes the degree ofopening of the butterfly valve 21 in this embodiment. As the amount ofvalve opening increases, the volume of exhaust air per unit time becomeslarger.

(1) First, at the time t1, the control unit 3 outputs to the valvecontroller 23 the valve opening signal which demands the butterfly valve21 to open 10% of the full-opening. In response, the valve controller 23makes the completely closed butterfly valve 21 partially open andoperate, whereby the vacuum pump 22 starts evacuating and depressurizingthe thin film forming chamber 11 by about 10% of the maximum volume ofexhaust air. The pressure inside the thin film forming chamber 11 thengradually decreases as denoted at the solid line (with APC) in the topsection of the graph in FIG. 3. In addition, at the time t1, the controlunit 3 sends a gas supply signal to the mass flow controller 14.Regardless of the pressure inside the thin film forming chamber 11, themass flow controller 14 maintains the flow rate of nitrogen gas which issupplied through the inlet 13.

(2) As depressurization achieves a desired pressure, in response to acontrol signal from the heater controller 61, the heater 6 is energizedand the first plate 4 is heated up to about 200° C., whereby thesubstrate W is heated up to a desirable temperature. Meanwhile, as forthe sheet film 8 as well, the heating lamps 53 turn on, the second plate5 is heated up to about 100° C. And the control unit 3 sends a signal tothe load motor 75, whereby the plate 5 starts moving upward or downward.The second plate 5 moves up to the position of the sheet film 8, and thestage 52 contacts the sheet film 8. The sheet film 8 is accordinglyheated up and strained, and the sheet film 8 sags in a wave-like shape.Noting this, in this embodiment, the film holding/straining unit 9strains the sheet film 8 and the wave-like sag is removed.

(3) At the same time of straining the sheet film 8, the first plate 4 asit is driven by the load motor 71 moves downward, the substrate W ispressed against the sheet film 8, and transfer of the insulation film 81to the substrate W is started. Further, receiving the valve openingsignal which demands the butterfly valve 21 to open 100%, the valvecontroller 23 completely opens the butterfly valve 21, and the vacuumpump 22 evacuates and depressurizes the thin film forming chamber 11 bythe maximum volume of exhaust air (time t2). Thus, as denoted at thesolid line (with APC) in the top section of the graph in FIG. 3,transfer of the insulation film 81 to the substrate W is carried outwhile the pressure inside the thin film forming chamber 11 rapidlydecreases. During the transfer (time t2 and later), the substrate W andthe sheet film 8 are pressed against each other under a predeterminedload for a constant period of time, with the butterfly valve 21 totallyopen. During this period as well, heating of the substrate W and thesheet film 8 continues so that the substrate W and the sheet film 8 stayat the predetermined temperature.

(4) As a series of loading operations finishes and the transferprocessing completes, the control unit 3 sends a signal to the loadmotors 71 and 75 in such a manner that zero load is applied, therebyreturning the first and the second plates 4 and 5 to their originalinitial positions. After the both plates 4 and 5 return to their initialpositions, the butterfly valve 21 is closed and the vacuum pump 22 isstopped.

(5) Next, waiting for the pressure inside the thin film forming chamber11 to return to the atmospheric pressure, the control unit sends a gassupply stop signal to the mass flow controller 14. The supply ofnitrogen gas to the thin film forming chamber 11 is thus stopped. Inaddition, the substrate W now integrated with the sheet film 8 with theinsulation film 81 held between the substrate W and the sheet film 8 isunloaded from the thin film forming chamber 11, the sheet film 8 ispeeled off from the substrate W, and the substrate W seating theinsulation film 81 is obtained.

As described above, according to this embodiment, the pressure controlunit 2 is disposed, and during the transfer comprised of the operations(1) through (3) above, the volume of exhaust air per unit time iscontrolled and the pressure inside the thin film forming chamber 11 isadjusted. In consequence, the insulation film 81 is transferredfavorably to the pattern-bearing surface of the substrate W. The reasonwill now be described in comparison with the conventional apparatus.

In the conventional apparatus, the pressure inside the thin film formingchamber 11 is controlled as denoted at the chain double-dashed line inFIG. 3 during execution of the transfer. That is, since the vacuum pump22 evacuates and depressurizes the thin film forming chamber 11 by themaximum volume of exhaust air immediately at the time t1, the pressureinside the thin film forming chamber 11 quickly decreases starting atthe time t1, and the substrate W and the sheet film 8 are heated and thesheet film 8 is strained in this depressurized state (state ofhigh-degree of vacuum). This progressively dries the insulation film 81and largely damages the fluidity of the insulation film 81, andtherefore, when transfer of the insulation film 81 to the substrate W isstarted at the time t2 with the substrate W pressed against the sheetfilm 8, the insulation film 81 may fail to be tightly adhered along thepattern-bearing surface of the substrate W.

In contrast, according to this embodiment, the problem above is solvedsince the degree of opening of the butterfly valve 21 is reduced beforestarting transfer of the insulation film 81 to the substrate W (from thetime t1 until the time t2). The controlling of the valve opening allowsthat an increase in degree of vacuum is suppressed therebefore wherebyevaporation of the solvent component contained in the insulation film 81is restrained and the fluidity of the insulation film 81 is ensured atthe start of the transfer (time t2). Further, since the butterfly valve21 is totally opened at the start of the transfer and the pressureinside the thin film forming chamber 11 is quickly decreased, it ispossible to transfer the insulation film 81 to the substrate W always ina low-pressure state (high-degree of vacuum) and to realize excellenttransfer. In addition, according to this embodiment, the atmosphereinside the thin film forming chamber 11 is exhausted through the exhaustvent 12 while supplying nitrogen gas into the thin film forming chamber11 through the mass flow controller 14. Hence, it is possible to eject acontaminant, unwanted vapor of the solvent and the like which floatwithin the thin film forming chamber 11 from within the thin filmforming chamber 11, and to realize excellent transfer.

The present invention is not restricted by the preferred embodimentabove, but may be modified appropriately to the extent matching theintention of the invention. For instance, although the preferredembodiment above requires to set the degree of opening of the butterflyvalve 21 to 10% of the full-opening from the time t1 until the time t2but to 100% at and after the time t2, the degree of the valve opening isnot limited to this. With the valve opening set such that at least thevolume of exhaust air per unit time prior to transfer of the insulationfilm 81 to the substrate W would be smaller than the volume of exhaustair per unit time during the transfer of the insulation film 81 to thesubstrate W, a similar effect is obtainable. However, since the level ofevaporation of the solvent may be different under the same pressuredepending on the material of the insulation film 81, it is desirable toset the degree of opening of the butterfly valve 21 in accordance withthe material of the insulation film 81.

In addition, although the degree of opening of the butterfly valve 21 isfixed to 10% of the full-opening before the start of the transfer (theperiod from the time t1 until the time t2) in this embodiment, thedegree of opening of the butterfly valve 21 may be changed successivelyor stepwise.

Further, while the pressure inside the thin film forming chamber 11 isadjusted and controlled using the butterfly valve 21 as the exhaustadjusting unit in this embodiment, used as the exhaust adjusting unit toreplace the butterfly valve 21 may be any pressure adjusting mechanismwhich is capable of adjusting the volume of exhaust air from the thinfilm forming chamber 11 to the vacuum pump 22.

Further, although the preferred embodiment above uses the vacuum pump 22as the exhausting unit, used as the vacuum pump 22 may any exhaustingmechanism which is capable of evacuating the thin film forming chamber.

Further, although the valve controller 23 controls the butterfly valve21 to thereby control the volume of exhaust air per unit time accordingto the preferred embodiment above, a voltage applied upon the vacuumpump 22 may be controlled to thereby control the volume of exhaust airper unit time as shown in FIGS. 4 and 5.

FIG. 4 is a drawing of other preferred embodiment of the thin filmforming apparatus according to the present invention. A major differenceof this embodiment from the preferred embodiment shown in FIG. 1 is thata drive voltage controller 24 is disposed instead of the butterfly valve21 and the valve controller 23. The other structure is the same. In thisthin film forming apparatus, as shown in FIG. 5, as a drive voltageapplied upon the vacuum pump 22 is controlled and the evacuatingcapability of the vacuum pump 22 is accordingly changed. That is, beforestarting transfer of the insulation film 81 to the substrate W (from thetime t1 until the time t2), the drive voltage applied upon the vacuumpump 22 is set low and the volume of exhaust air per unit time issuppressed, whereby an increase in degree of vacuum is suppressed. Thissuppresses evaporation of the solvent component contained in theinsulation film 81, and ensures the fluidity of the insulation film 81at the start of the transfer (time t2). On the other hand, starting atthe start of the transfer, the drive voltage applied upon the vacuumpump 22 is increased up to a maximum applied voltage Vmax, to therebyincrease the volume of exhaust air per unit time. This rapidly decreasesthe pressure of the thin film forming chamber 11 and allows to transferthe insulation film 81 to the substrate W always in a low-pressure state(high-degree of vacuum), which realizes excellent transfer.

While the foregoing demands to set the applied voltage upon the vacuumpump 22 to 10% of the maximum applied voltage Vmax from the time t1until the time t2 but to the maximum applied voltage Vmax at and afterthe time t2, the applied voltage is not limited to this. With theapplied voltage set such that at least the volume of exhaust air perunit time prior to transfer of the insulation film 81 to the substrate Wwould be smaller than the volume of exhaust air per unit time during thetransfer of the insulation film 81 to the substrate W, a similar effectis obtainable. However, since the level of evaporation of the solventmay be different under the same pressure depending on the material ofthe insulation film 81, it is desirable to set the applied voltage inaccordance with the material of the insulation film 81. Alternatively,the applied voltage may be changed successively or stepwise.

Although the preferred embodiments above demand that the first plate 4functions as the substrate holding means and the second plate 5functions as the film holding means, the second plate 5 may function asthe substrate holding means and the first plate 4 may function as thefilm holding means.

Further, although the sheet films 8 are formed in the shape of a diskand applied to a thin film forming apparatus in which the sheet films 8are supplied to the first and the second plates 4 and 5 one afteranother and pressed according to the preferred embodiments above, thepresent invention is readily applicable to a thin film forming apparatuswhich uses a roll-like sheet film. Further, although the first and thesecond plates 4 and 5 are raised and lowered using the load motors 71and 75 in the preferred embodiments above, only one of the first and thesecond plates 4 and 5 may be moved. Further, although the load motors 71and 75 are used as a loading mechanism to apply a load, this is notlimiting. Any other means may be used instead as a mechanism of pressingthe first and the second plates 4 and 5 against each other.

Further, although the sheet film 8 formed by a thermoplastic resin filmis used in the preferred embodiments above, this is not limiting. Ametallic film, a flat plate or the like may be used instead, of course.

Further, although an insulation film is disposed on the sheet film 8 inthe preferred embodiments above, the insulation film may be other thinfilm which can be disposed on the sheet film, such as a metallic thinfilm or the like. Further, while the preferred embodiments above areexamples that a thin film is formed on a semiconductor substrate, thisis not limiting. The present invention is of course applicable to amounting substrate, a substrate for liquid crystals and any othersubstrates which are used in relevance to an electronic componentmaterial, such as a multi-tip module.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiment, as well asother embodiments of the present invention, will become apparent topersons skilled in the art upon reference to the description of theinvention. It is therefore contemplated that the appended claims willcover any such modifications or embodiments as fall within the truescope of the invention.

1-9. (canceled)
 10. A thin film forming method in which a substrate anda sheet film are pressed against each other within a thin film formingchamber and a thin film disposed on a substrate-side major surface ofsaid sheet film is transferred to said substrate, characterized in thatthe pressure inside said thin film forming chamber becomes differentbetween before and during the transfer.
 11. The thin film forming methodof claim 10, wherein reduction of the pressure inside said thin filmforming chamber is started from before the transfer, and in response tothe start of the transfer, the pressure inside said thin film formingchamber is decreased smaller than that before the transfer.
 12. The thinfilm forming method of claim 11, wherein the volume of exhaust air fromsaid thin film forming chamber per unit time is adjusted and thepressure inside said thin film forming chamber is accordinglycontrolled.